# [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)

Fabio Azzarello iw8qku at amsat.org
Wed Apr 21 22:45:24 PDT 2010

```Hi all,
I'm pleased of all those replies... but
as I wrote in my previous email ( I agree with Mr. Bruninga ) "ERP is about
243 MW" and
that comes from the conversion from dBi to dBd. That's all.
No Losses. No difference in decimals punctuation.

That's my conclusion... think it is the right one.

73s
Fabio
IW8QKU

On Wed, Apr 21, 2010 at 1:46 PM, Fabio Azzarello <iw8qku at amsat.org> wrote:

> Hello,
> thanks for the reply, but now I have another question.
> I'm not good enough with those numbers!
>
> If the calculated ERP is about 243 MW... which derives from changing from
> dBi to dBd (60dBi - 2.14),
> the part I don't understand is:
>
> "*Since the given ERP is 243,902,443 Million Watts (see below)
> and since 60 dB is equivalent to 1000000 (one Million) time in
> power it comes out that the power reaching the feed of the dish is:
> 243902443 / 1000000 = 243 watt
>
> The rest of the power 400-243 = 157 watt is lost in the feed line.*"
>
> How do they have feeder losses?
>
> 73s
> Fabio
> iw8qku
>
>
>
> On Wed, Apr 21, 2010 at 8:45 AM, Mateusz <sq7dqx at poczta.onet.pl> wrote:
>
>>
>> 60dBi is abt 57dB
>> It means 10exp5,7
>> ERP was 400x10exp5,7 W
>>
>> ----- Original Message ----- From: "Fabio A" <iw8qku at amsat.org>
>> To: <AMSAT-BB at amsat.org>
>> Sent: Tuesday, April 20, 2010 8:26 PM
>> Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
>>
>>
>>  Hello all,
>>> just a curiosity, how did you found that the ERP is "... 243,902,443
>>> Million
>>> Watts".
>>>
>>> Thanks
>>>
>>> 73s
>>> Fabio
>>> iw8qku
>>>
>>>>
>>>>
>>>> ... snip ...
>>>>
>>>
>
```